Separation of milk proteins into fractions rich in casein or whey proteins by cross flow filtration

Partially defatted skim milk was separated into casein-rich and whey protein-rich fractions using ceramic membranes. Among the membrane pore sizes tested, the 0.05 mu m membrane retained all the caseins and allowed only the beta-lactoglobulin, alpha-lactalbumin and smaller molecular weight components to pass through. Permeate Bur was primarily affected by cross flow velocity while transmembrane pressure had little effect. The optimal operating conditions for this separation were 5.4 m s(-1) and 138 kPa at 50 degrees C. The permeate showed excellent foam forming properties at a protein content of 0.31%. The foaming ability of the permeate was further evaluated by first dialyzing it and then concentrating to 5% protein content. The overrun value for the concentrated permeate was > 1000 which is comparable to the values cited for egg white and better than those cited for products made form cheese whey. The gelation property of the dialyzed and concentrated permeate was also very good. (C) 1999 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.